The objective was to detect cows with elevated postpartum nonesterified fatty acids (NEFA) and β-hydroxybutyrate (BHBA) concentrations, with or without concurrent hyperketonemia, and identify genomic regions associated with development of hyperketonemia in periparturient Holstein cows. The study population consisted of cows from 2 different trials: In the first study, 63 cows (parity ≥2) were enrolled and blood was collected from 3 to 16 d in milk. In the second study, 84 cows (parity ≥2) were enrolled and sampled from −21 d to +21 d relative to calving. Blood samples were tested for NEFA and BHBA concentration. Hyperketonemia was defined as a BHBA concentration ≥1.2 mmol/L. All BHBA and NEFA measurements were grouped using incremental area under the curve (AUC) to identify individuals with the most variation. Holstein cows were genotyped on the Illumina Bovine High-density (777K) Beadchip. Quality control filtering produced (n = 522,231) single-nucleotide polymorphism (SNP). A genomic wide association study was performed to establish correlation between low frequency SNP (<5%) and development of hyperketonemia using Golden Helix software. The linear regression R² = 0.21 suggested a low strength correlation between BHBA AUC and NEFA AUC concentration. Although a small sample size, given that these cows were managed under similar conditions, multiple SNP associated with high concentrations of BHBA were found (Table 1). These results might improve genetic selection criteria to identify high-risk animals and develop preventative measures to decrease hyperketonemia development. Table 1.Regions and candidate genes associated with development of hyperketonemia

Index	Chr.	Region start (bp)	Region end (bp)	−Log10 (P-value)	Genes
1	2	12,122,028	12,128,393	5.086193951	RRAGA
2	2	104,958,840	104,958,840	5.410113588	PECR; IGFBP2 and IGFBP5
3	3	93,634,769	93,634,769	5.031371132	LRP8; CPT2 and SCP2
6	21	14,153,070	14,153,070	5.111968697	CHD2
7	21	16,112,290	17,017,717	6.451923226	SV2B